The access to the collective resource can be controlled by means of an interface. The interface uses an access scheme in accordance with which the functions can access the collective resource.
A possible access scheme is characterized by a repetitive access pattern. The access pattern comprises a plurality time slots. Each time slot is allocated to a given function. This means that the relevant function has access to the collective resource during this time slot. Let it be assumed that a functional system has three functions A, B and C. An access pattern may give access to the function A during two units of time, subsequently to B during one unit of time and finally to C during three units of time. This pattern thus comprises six units of time in total and is repeated every six units of time. Such an access scheme will be referred to hereinafter as a fixed access scheme.
Another possible access scheme is characterized by an order of priority. A function should submit a request to access the collective resource. The interface receives all the requests. From the functions having a pending request it allows the function having the highest priority to access the collective resource. Let it be assumed again that a functional system has three functions A, B and C. Let the order of priority be A, B, C. In this case, the function A will have access to the collective resource independently of the fact that the function B or C has a pending request. The function B will have access to the collective resource provided that there is no pending request from the function A. The function C will have access to the collective resource provided that there is no pending request from the function A or B. Such a scheme will be referred to hereinafter as a priority access scheme.
The two access schemes described hereinbefore are mentioned in the international Patent Application published under the number WO95/31874. The aforementioned Application relates to an MPEG decoder.